The present invention relates to a fusible interlining composed of a textile interlining web (such as nonwoven fabrics, woven fabrics, knitted fabrics) which is coated on one side with double-layered adhesive dots that are composed of bottom and upper dots (2,3), the bottom dots facing the interlining web and the upper dots being located above the bottom dots.
European Patent Application EP-A 0 940 461 describes a cross-linkable hot melt adhesive composition for coating and/or laminating fabrics, of which one cross-linking component is embedded in a polyolefin matrix, and the reactive components react only in the melt, forming cross-links. The specified cross-linking components are isocyanates or epoxides having molar masses between 2000 and 6000 grams per mol. In this context, the actual hot melt adhesive composition is designed to be composed of amino-terminated copolyamide or copolyester, which are used both in the bottom and upper dots. This approach has the disadvantage that, on one hand, the cross-linking component must first be incorporated, with considerable effort, in a polyolefin matrix which protects from moisture, and that the amino-terminated copolyamides have a strong tendency to yellow.
German Patent Application DE-A 195 10 316 describes a hot melt adhesive composition which is used for coating fabrics, in particular, interlining fabrics, and contains a mixture of thermoplastic hot melt adhesive and epoxide, the epoxide content being 5 to 25 percent by weight. This hot melt adhesive composition is used as a single-dot coating, involving disadvantages with respect to bleed-through of the hot melt adhesive composition in the case of very thin interlining fabrics.
Moreover, U.S. Pat. No. 5,677,038 describes two-layer hot melt adhesive compositions, whose bottom dot is composed of a copolyamide or copolyester applied in the form of a paste and whose upper dot is composed of a mixture of 0 to 25 by weight of a copolyamide, 50 to 95 percent by weight of a copolyester, and 5 to 25 percent by weight of an epoxide. For textile materials bonded using this hot melt adhesive system, the specified separation force values were below 10 N/5 cm, these values further decreasing after one washing. Besides the documents mentioned, further double-layered adhesive compositions are known from German Patent Applications DE-A 22 14 236, DE-A 22 31 723, DE-A 25 36 911 and DE-A 32 30 579. By using relatively light nonwoven fabrics, that is, nonwoven fabrics having a low weight per unit area, very soft laminates are indeed obtained, but the nonwoven fabrics have the disadvantage that they are very sensitive with respect to back-riveting of the hot melt adhesive compositions. In this context, “back-riveting” is understood to refer to an unwanted bonding between two interlining fabrics, which can occur when the interlining web coated with the adhesive composition of the dots, hereinafter referred to as fusible interlining, is bonded to the shell fabric using the interior-sandwich fixing method. In this context, the interior sandwich is composed of the following layer sequence: shell fabric, coated interlining web as well as coated interlining web, shell fabric, which means that the uncoated sides of the of the interlining webs rest against one another. The amount of coating applied per square meter of interlining web was, in fact, reduced from 18–25 g/m2 previously to 7–15 g/m2. However, it should be reduced further in view of the softness of the textile laminate. Along with the high demands made on adhesion and resistance of the laminate, at the same time more importance is attached to the feel. In particular, with regard to the care properties of a textile laminate, there is a requirement for it to withstand several washings at washing temperatures up to 60° C.
Double-dot systems which are used for coating interlining fabrics and which exhibit improved adhesion combined with a reduced back-riveting tendency by using epoxy resins in the bottom dots are, in fact, known from German Patent Document DE 100 27 957. In this context, however, it is a disadvantage that the feel of the interlining is negatively affected by the use of semicrystalline thermoplastics in combination with epoxides in the bottom dot. This means that the feel becomes firmer.